This invention relates to a self-locking dowel pin. In more detail, the invention relates to an assembly including a substrate member, a member to be immobilized and a dowel pin which locks the members together. The invention also relates to a method of locking two abutting members together.
A dowel pin is defined in Webster's Third New International Dictionary (Unabridged) as "a headless smooth or barbed pin usually of circular section fitting into corresponding holes in abutting pieces to act as a temporary fastener or to keep them permanently in their proper relative positions". Dowel pins are frequently used in nuclear reactors to lock two abutting members together as when a member to be immobilized is locked to a substrate member. In view of the nature of the use -- the members are subject to heat cycling and vibration over a long period of time -- the dowel pins must be emplaced so as to lock the two members together with no possibility the dowel pin could slip out of place. Also, it is essential that the pieces of a dowel pin that has sheared due to relative movement of the members remain in place. A loose dowel pin or piece of a dowel pin in a nuclear reactor could be disastrous.
In practice it has been found necessary to weld dowel pins in place with a 360.degree. weld when the dowel pin is used in a power reactor. For many nuclear reactor applications where the dowel pin is in a "sensitive" location, distortions created by welding constitute a serious problem. Since 360.degree. welding has heretofore been necessary, careful nondestructive testing of the welds has been necessary to ensure that damaging distortion has not occurred.